Lichen planus is a chronic cutaneous and mucosal disease characterized by the infiltration of cluster of differentiation (CD) CD8 T lymphocytes, localized under the basal membrane and associated with apoptosis of basal keratinocytes, suggesting a reactivity of T lymphocytes toward keratinocyte antigen(s), so far unidentified. In a recent study, the research team at Institut Pasteur has demonstrated in a peculiar clinical form of lichen planus (erosive lichen planus), that the immunogenic target of CD8 T lymphocytes could be the immunodominant peptide of Human Papilloma Virus (HPV) 16.